Thermal Performance Of A New Type Assembly Composite Wall Panels For Village Dwellings

The amount of Chinese village dwellings is so huge in this country.It is a significant topic of developing the energy efficiency for village dwellings in the field of green building research.In this paper,a new type of assembled multi-ribbed composite wallboards which have complex structure are introduced.However,many problems in its application,thermal performance and energy efficiency need to be resolved.Three levels will be discussed as follows:1.Discussing the feasibility of popularizing the multi-ribbed composite walls in the traditional villages preliminarily: The technical applicability of this walls and their insulation technology can meet the promotion conditions,and standardized fabricated technology and dwellings' individual needs can be harmonized greatfully.2.Calculation methods are discussed and corrected of the heat transfer coefficient and the average thermal resistance: Three methods such as “One-dimensional calculation method”,“Three-dimensional numerical simulation analysis in ANSYS” and “Guard hot box test” are comparative analyzed and differences are evaluated.Besides,the heat transfer laws of this wallboards are explored and the one-dimensional algorithm is modified.First,the three kinds of thermal resistance calculation methods are discussed from the theoretical level,and the heat transfer mechanism of this inhomogeneous wall is analyzed.The 1-D formula recommended by codes is based on the 1-D heat transfer theory.Its accuracy,especially in extremely inhomogeneous walls in calculating the heat transfer coefficient,is unknown;The 3-D thermal analysis of ANSYS has high accuracy and reproducibility because it is a numerical simulation based on 3-D heat transfer theory;The guard hot box test is a kind of experiment method with strong reliability and complicated operating conditions.Compared with this three methods: 1-D simplification algorithm has the uncertainty.3-D simulation method with ANSYS is in good agreement with the experimental test value,which can be used as an important research tool to correct the 1-D algorithm.Then,starting argumentation by the experimental method.The thermal conductivity of drying aerated concrete was measured by the TPMBE-300 Twin-plate Device.In addition,the thermal conductivity of reinforced concrete under the same rebar volume fraction was obtained.Then the heat transfer coefficient,or average thermal resistance were measured with guard hot box: A 1:2(1m × 1m × 0.1m)scale model which in accordance with the actual wall was made in view of the size of test sample Measured by guard hot box under steady state.Finally,3-D heat transfer simulations of ANSYS is used to simulate for the multi-ribbed composite wall under the actual working conditions.The results show that the thermal conductivity ratio of each composite material,the different geometrical structure types of walls and the thermal resistance of insulation layer are the main factors that make the 1-D algorithm loss of precision.When the correction coefficient value ? of the 1-D simplified algorithm is counter calculate under the same condition we found that: The 3-D “lateral heat transfer” has a great influence on the 1-D algorithm when the thickness of composite wall insulation layer is small,and as the insulation layer increasing,the difference between the 3-D lateral heat transfer and the 1-D algorithm is gradually weakened.Then eight kinds of typical multi-ribbed composite walls with different constructions were screened.The 3-D results simulated by ANSYS were used to counter calculate the ? with 1-D calculation of various structural types and insulation.Lastly,the 1-D simplified calculation formula of the wallboards is corrected,so that it can achieve the actual energy-saving calculation needs,also can meet the accuracy requirements.3.The evaluation of this walls' thermal performance was enlarged to the macro level,and discussing the thermal performance and energy efficiency effect of this wall in a Hui-style residential demonstration projects.Firstly,the thermal indexes,such as the heat transfer coefficient and the average thermal resistance of the assembled composite walls in this scheme,are calculated by the above results.Then,the winter indoor thermal environment test is carried out,and the test results are analyzed in detail.Finally,we use Design Builder to analyze the energy consumption of this scheme,evaluating the thermal performance and energy efficiency of the multi-ribbed composite walls in the demonstration project.Then draw the conclusion that what the dynamic performance and improvement measures of the multi-ribbed composite wall in the demonstration project are.Laying the theoretical foundation for promoting this system to Chinese traditional village and promoting the green building concept.